Lpc2000

Hi

I have a question about the PWMPR Register (frequency,  LPC2292).

To generate a ramp for an stepper motor, i want change the frequency 
during the runtime of the PWM.

The Question is:
When i change the PWMPR to another value when the PWM is enabled, at 
which state/time is the new PWMPR active ?

Thanks & best regards

Thomas